DCE-MRI of the liver: reconstruction of the arterial input function using a low dose pre-bolus contrast injection

Abstract

Purpose: To assess the quality of the arterial input function (AIF) reconstructed using a dedicated pre-bolus low-dose contrast material injection imaged with a high temporal resolution and the resulting estimated liver perfusion parameters.

Materials and methods: In this IRB-approved prospective study, 24 DCE-MRI examinations were performed in 21 patients with liver disease (M/F 17/4, mean age 56 y). The examination consisted of 1.3 mL and 0.05 mmol/kg of gadobenate dimeglumine for pre-bolus and main bolus acquisitions, respectively. The concentration-curve of the abdominal aorta in the pre-bolus acquisition was used to reconstruct the AIF. AIF quality and shape parameters obtained with pre-bolus and main bolus acquisitions and the resulting estimated hepatic perfusion parameters obtained with a dual-input single compartment model were compared between the 2 methods. Test-retest reproducibility of perfusion parameters were assessed in three patients.

Results: The quality of the pre-bolus AIF curve was significantly better than that of main bolus AIF. Shape parameters peak concentration, area under the time activity curve of gadolinium contrast at 60 s and upslope of pre-bolus AIF were all significantly higher, while full width at half maximum was significantly lower than shape parameters of main bolus AIF. Improved liver perfusion parameter reproducibility was observed using pre-bolus acquisition [coefficient of variation (CV) of 4.2%-38.7% for pre-bolus vs. 12.1-71.4% for main bolus] with the exception of distribution volume (CV of 23.6% for pre-bolus vs. 15.8% for main bolus). The CVs between pre-bolus and main bolus for the perfusion parameters were lower than 14%.

Conclusion: The AIF reconstructed with pre-bolus low dose contrast injection displays better quality and shape parameters and enables improved liver perfusion parameter reproducibility, although the resulting liver perfusion parameters demonstrated no clinically significant differences between pre-bolus and main bolus acquisitions.

Trial registration: ClinicalTrials.gov NCT01600105.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1. Flow diagram showing pre-bolus and main bolus AIF acquisition and processing for DCE-MRI of the liver in a 67 year-old male patient with HCV.

The pre-bolus protocol consists of a high temporal resolution 2D acquisition (0.2 s). An ROI is then placed in the abdominal aorta and the concentration curve is extracted. This curve is used to reconstruct pre-bolus AIF. Main bolus imaging protocol consists of 3D acquisition with higher spatial resolution/lower temporal resolution (3.2 s). ROIs are placed on the abdominal aorta, portal vein and liver parenchyma. Pre-bolus AIF curve (bottom) demonstrates better quality compared to main bolus AIF (top).

Figure 2. AIF reconstruction using measured gadolinium concentration in the abdominal aorta after pre-bolus injection in a 52 year-old male patient with HCV.

The reconstructed AIF consists of the addition of scaled time-shifted versions of the response to low-dose pre-bolus injection of contrast agent. The concentration curve in the abdominal aorta displays rapid oscillations superimposed to the expected signal shape due to in-flow effects, which are minimized by the selection of the small flip angle and a coronal oblique acquisition that contains the abdominal aorta.

Figure 3. Diagram depicting calculated AIF (arterial input function) parameters (A).

An example is shown in a 67-year-old patient with HCV (same patient as in Fig. 1). Pre-bolus AIF (B) and main bolus AIF (C). Pre-bolus AIF demonstrates higher peak concentration, upslope and AUC60, shorter TTP and smaller FWHM (values are given on the figures).